Abstract:

A multiphase pump includes a master cylinder having a first port adjacent
to a first end of the master cylinder, and a second port adjacent to a
second end of the master cylinder connected to a source of hydraulic
fluid. A master piston is positioned within the master cylinder. A slave
cylinder is adjacent to each of the first and second ends of the master
cylinder. Each slave cylinder has a first input port and a first output
port adjacent to a first end of each slave cylinder, and a second input
port and a second output port adjacent to a second end of each slave
cylinder. Each first input port and second input port is adapted to
connect to a source of gas to be compressed. A slave piston is positioned
within each slave cylinder and is connected to the master cylinder such
that movement of the master piston results in movement of each slave
piston.

Claims:

1. A multiphase pump, comprising:a master cylinder having a first port
adjacent to a first end of the master cylinder, and a second port
adjacent to a second end of the master cylinder, each of the first port
and the second port being connected to a source of hydraulic fluid;a
master piston positioned within the master cylinder;a slave cylinder
adjacent to each of the first end of the master cylinder and the second
end of the master cylinder, each slave cylinder having a first input port
and a first output port adjacent to a first end of each slave cylinder,
and a second input port and a second output port adjacent to a second end
of each slave cylinder, each first input port and second input port being
adapted to connect to a source of gas to be compressed; anda slave piston
positioned within each slave cylinder, each slave piston being connected
to the master cylinder such that movement of the master piston results in
movement of each slave piston.

2. The multiphase pump of claim 1, wherein the diameter of the master
cylinder is less than the diameter of the slave cylinders.

3. The multiphase pump of claim 1, wherein the diameter of the master
cylinder is greater than the diameter of the slave cylinders.

4. The multiphase pump of claim 1, wherein one cycle of the master piston
results in four compression strokes.

5. The multiphase pump of claim 1, wherein each of the input ports and the
output ports are one-way valves.

6. The multiphase pump of claim 1, wherein each first input port and
second input port is adapted to connect to a natural gas-producing well.

7. The multiphase pump of claim 1, wherein the each of the first outputs
and the second outputs are adapted to connect to a natural gas storage
tank or a natural gas pipeline.

8. The multiphase pump of claim 7, wherein the source of hydraulic fluid
is driven by the power source for the natural gas-producing well.

9. A multiphase pump, comprising:a master cylinder having a first port
adjacent to a first end of the master cylinder, and a second port
adjacent to a second end of the master cylinder, each of the first port
and the second port being connected to a source of hydraulic fluid;a
master piston positioned within the master cylinder, the position of the
master cylinder being controlled by the source of hydraulic fluid;a slave
cylinder adjacent to each of the first end of the master cylinder and the
second end of the master cylinder, the diameter of each slave cylinder
being greater than the diameter of the master cylinder, each slave
cylinder having a first input port and a first output port adjacent to a
first end of each slave cylinder, and a second input port and a second
output port adjacent to a second end of each slave cylinder, each first
input port, second input port, first output port and second output port
being one-way valves, each first input port and second input port being
adapted to connect to a natural gas-producing well, each first output
port and each second output port being adapted to connect to a natural
gas storage tank or a natural gas pipeline; anda slave piston positioned
within each slave cylinder, each slave piston being connected to the
master cylinder such that movement of the master piston results in
movement of each slave piston, and such that one cycle of the master
piston results in four compression strokes.

Description:

[0003]There is provided a multiphase pump includes a master cylinder
having a first port adjacent to a first end of the master cylinder, and a
second port adjacent to a second end of the master cylinder. Each of the
first port and the second port are connected to a source of hydraulic
fluid. A master piston is positioned within the master cylinder. A slave
cylinder is adjacent to each of the first end of the master cylinder and
the second end of the master cylinder. Each slave cylinder has a first
input port and a first output port adjacent to a first end of each slave
cylinder, and a second input port and a second output port adjacent to a
second end of each slave cylinder. Each first input port and second input
port is adapted to connect to a source of gas to be compressed. A slave
piston is positioned within each slave cylinder. Each slave piston is
connected to the master cylinder such that movement of the master piston
results in movement of each slave piston.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004]These and other features will become more apparent from the
following description in which reference is made to the appended
drawings, the drawings are for the purpose of illustration only and are
not intended to be in any way limiting, wherein:

[0005]FIG. 1 is a schematic view of the multiphase pump in a first
position.

[0006]FIG. 2 is a schematic view of the multiphase pump in a second
position.

[0008]A multiphase pump, generally identified by reference numeral 10,
will now be described with reference to FIGS. 1 and 2.

[0009]Structure and Relationship of Parts:

[0010]Referring to FIG. 1, multiphase pump 10 includes a master cylinder
12 with a master piston 13 within. Master cylinder 12 has a first port 14
adjacent to a first end 16, and a second port 18 adjacent to a second end
20. First port 14 and second port 18 are connected to a source 22 of
hydraulic fluid, which includes a power source for applying pressure to
circulate hydraulic fluid to and from first and second ports 14 and 18.
In some situations, it may be convenient to use an existing power source
to circulate hydraulic fluid, such as an engine driving a pump for a
well.

[0011]There is also a slave cylinder 30 with a slave piston 31 within
positioned adjacent to each of first end 16 of master cylinder 12 and
second end 20 of master cylinder 12. Each slave cylinder 30 has a first
input port 32 and a first output port 34 adjacent to a first end 36, and
a second input port 38 and a second output port 40 adjacent to a second
end 42. Each input and output port 32, 34, 38 and 40 are one way valves
to allow a gas to be compressed to enter input ports 32 and 38, and exit
output ports 34 and 40. Each input port 32 and 38 is adapted to connect
to a source of fluid 43 to be pumped, such as a wellhead 44, and each
output port 34 and 40 is connected to a transport or storage system, such
as a pipeline 46 or a storage tank. The design of multiphase pump allows
it to be used for various fluids. Thus, it may be connected to a natural
gas-producing wellhead, in which case it acts as a hydraulic compressor.
It may also be used to pump liquids, or a combination of fluids. When
pumping fluids from a wellhead, there will often be a separator package
(not shown) between output ports 34 and 40 and pipeline 46 or storage
tank to removed the unwanted phase.

[0012]Slave piston 31 is connected to master cylinder 12 by a rod 48 or
other rigid connector, such that movement of master piston 13 results in
movement of each slave piston 31. Seals 50 are used to prevent hydraulic
fluid or gas from passing between master cylinder 12 and slave cylinders
30.

Operation:

[0013]As hydraulic fluid is pumped into first port 14, master piston 13 is
moved from first end 16, as shown in FIG. 1, toward second end 18, as
shown in FIG. 2. Rod 48 causes each slave piston 31 to move accordingly.
Master piston 13 and slave pistons 31 are moved back by pumping hydraulic
fluid into second port 18. Because of a slave cylinder 30 being
positioned at each end of master cylinder 12, and each slave cylinder
having two input ports 32 and 38 and two output ports 34 and 40, one
cycle of master piston 13 results in four pump strokes.

Variations:

[0014]Referring to FIGS. 1 and 2, the diameter of master cylinder 12 is
less than the diameter of slave cylinder 30. This is particularly useful
when pump 10 is used as a compressor, as it allows more gas to be
compressed with a smaller volume of hydraulic fluid being pumped to and
from master cylinder 12 than would otherwise be the case. Multiphase pump
10 may also be designed with different relative volumes of slave cylinder
30 and master cylinders 12. For example, as shown in FIG. 3, master
cylinder 12 may be larger than slave cylinders 30, which would be useful
for pumping heavy fluids, when there is a greater force is to be
overcome, etc.

[0015]Multiphase pump 10 may also be used for other pumping and
compression applications, for example, it may be used for pumping water,
or it may be positioned downhole to pump fluid. If it is used as a
downhole pump, it is preferred to design pump 10 that rod 48 be hollow,
and that output ports 34 and 40 be located on rod 48, such that fluid is
pumped from slave cylinders 30 through rod 48 to surface.

Advantages:

[0016]Multiphase pump 10 may be used to pump liquids, gases, or
combinations thereof. When gases are pumped, multiphase pump 10 may act
as a hydraulic compressor. Furthermore, the mechanical advantage of pump
10 may be changed by set by simply designing pump 10 with a larger
smaller slave cylinders 30 relative to master cylinder 12.

[0017]It has also been found that it is possible to obtain full strokes in
slave cylinders 30 without having to worry about a blowout by limiting
the maximum hydraulic pressure applied to master cylinder 12.

[0018]In this patent document, the word "comprising" is used in its
non-limiting sense to mean that items following the word are included,
but items not specifically mentioned are not excluded. A reference to an
element by the indefinite article "a" does not exclude the possibility
that more than one of the element is present, unless the context clearly
requires that there be one and only one of the elements.

[0019]It will be apparent to one skilled in the art that modifications may
be made to the illustrated embodiment without departing from the spirit
and scope defined in the Claims.